As the technology of robotics progresses, the safety between humans and robots becomes a concern for developers and researchers. In the course of interaction between a human and a robot, it becomes more difficult to detect and handle a region that may have a risk of safety. Conventional techniques in this regard make a separation of the human and the robot, based on a single fixed region. Unfortunately, the separation for every region may vary inevitably, and monitoring and managing in real-time and flexibility may become too difficult to achieve.